Pipe network calculation forms the basis of hydraulic planning for heating, cooling, and sanitary systems. Based on calculated heat or volume flow rates, pipe diameters are selected to keep flow velocities within acceptable limits while minimising noise and pressure losses. The most unfavourable branch, the one with the highest pressure drop, determines the required pump head. Parallel branches are hydraulically balanced using presetting valves or differential pressure controllers. Relevant standards include DIN EN 12828 and VDI 2073. Modern planning software enables fully automated calculation of even complex looped networks.